ffprobe -show_streams input.mp4
[STREAM]
index=0
codec_name=hevc
codec_long_name=H.265 / HEVC (High Efficiency Video Coding)
profile=Main
codec_type=video
...
level=120
...
ffprobe -show_streams input.mp4
[STREAM]
index=0
codec_name=hevc
codec_long_name=H.265 / HEVC (High Efficiency Video Coding)
profile=Main
codec_type=video
...
level=120
...
ffprobe indicates the stream codec is H.265 a.k.a. HEVC. The correct Wiki link is https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding_tiers_and_levels
The codec standard requires the level be multiplied by 30 before it is stored in the bitstream. So, a readout of 120 corresponds to 120/30 = level 4