MongoDB connection suddenly stopped working

I have a Spring Boot app connected to MongoDB running on Heroku and had no problems with it up until few days ago. I didn't change anything in the code or wherever. Locally I have the same build that's all good on heroku.

Stacktrace is as follows

Exception in monitor thread while connecting to server <collectionname>-shard-00-00.dhetx.mongodb.net:27017

com.mongodb.MongoSocketWriteException: Exception sending message
    at com.mongodb.internal.connection.InternalStreamConnection.translateWriteException(InternalStreamConnection.java:550) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnection.sendMessage(InternalStreamConnection.java:432) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnection.sendCommandMessage(InternalStreamConnection.java:272) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:256) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.CommandHelper.sendAndReceive(CommandHelper.java:83) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.CommandHelper.executeCommand(CommandHelper.java:33) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnectionInitializer.initializeConnectionDescription(InternalStreamConnectionInitializer.java:103) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnectionInitializer.initialize(InternalStreamConnectionInitializer.java:60) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:128) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:117) ~[mongodb-driver-core-4.0.5.jar:na]
    at java.base/java.lang.Thread.run(Thread.java:830) ~[na:na]
Caused by: javax.net.ssl.SSLHandshakeException: extension (5) should not be presented in certificate_request
    at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:131) ~[na:na]
    at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:117) ~[na:na]
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:311) ~[na:na]
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:267) ~[na:na]
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:258) ~[na:na]
    at java.base/sun.security.ssl.SSLExtensions.<init>(SSLExtensions.java:90) ~[na:na]
    at java.base/sun.security.ssl.CertificateRequest$T13CertificateRequestMessage.<init>(CertificateRequest.java:818) ~[na:na]
    at java.base/sun.security.ssl.CertificateRequest$T13CertificateRequestConsumer.consume(CertificateRequest.java:922) ~[na:na]
    at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:396) ~[na:na]
    at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:444) ~[na:na]
    at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:422) ~[na:na]
    at java.base/sun.security.ssl.TransportContext.dispatch(TransportContext.java:181) ~[na:na]
    at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:164) ~[na:na]
    at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1460) ~[na:na]
    at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1368) ~[na:na]
    at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:437) ~[na:na]
    at java.base/sun.security.ssl.SSLSocketImpl.ensureNegotiated(SSLSocketImpl.java:878) ~[na:na]
    at java.base/sun.security.ssl.SSLSocketImpl$AppOutputStream.write(SSLSocketImpl.java:1240) ~[na:na]
    at com.mongodb.internal.connection.SocketStream.write(SocketStream.java:99) ~[mongodb-driver-core-4.0.5.jar:na]
    at com.mongodb.internal.connection.InternalStreamConnection.sendMessage(InternalStreamConnection.java:429) ~[mongodb-driver-core-4.0.5.jar:na]
    ... 9 common frames omitted

and application.properties

server.port=${PORT:8080}
spring.data.mongodb.uri=mongodb+srv://<login>:<pasword>@<collectionname>.dhetx.mongodb.net/<collectionname>?retryWrites=true&w=majority
spring.data.mongodb.database=<collectionname>
logging.level.org.atmosphere = warn
spring.mustache.check-template-location = false

I have all IPs whitelisted on Atlas thanks to 0.0.0.0/0, so that's probably not it (and it has been working before).

Did anyone has similar problems? I have no idea what to do. Grateful for any answers.