Follow-up question for: Grime-like blocking compression artifacts on the decompressed video (H.264).
Context: while watching videos from time to time I continue notice the presence of compression artifacts, which usually last a few fractions of a second. A few examples (all of them are taken from YouTube, so I guess that the video is H.264 compressed):
Questions for experienced users / developers:
Can you determine the (potential) reasons of such compression artifacts just by looking on them?
Are such compression artifacts caused by bugs in the encoders or by bugs in the decoders?
Can such compression artifacts be avoided? How?
Reason of the question / concern: It is very surprising that in 2021 it is still possible to have such compression artifacts. I supposed that they are left in the 20th century.