How to understand main log of CP

Just today I got these in CP main log file. How to interpret it?

[02.09.2021_13-09-23] Request body exceeded settings.DATA_UPLOAD_MAX_MEMORY_SIZE.
[02.09.2021_13-09-25] Expecting value: line 1 column 1 (char 0)
[02.09.2021_13-33-25] ‘utf-8’ codec can’t decode byte 0x89 in position 724: invalid start byte
[02.09.2021_13-33-27] ‘utf-8’ codec can’t decode byte 0x89 in position 721: invalid start byte
[02.09.2021_13-33-28] ‘utf-8’ codec can’t decode byte 0x89 in position 722: invalid start byte
[02.09.2021_13-33-29] ‘utf-8’ codec can’t decode byte 0x89 in position 722: invalid start byte
[02.09.2021_13-33-29] ‘utf-8’ codec can’t decode byte 0x89 in position 723: invalid start byte
[02.09.2021_13-33-31] Expecting value: line 1 column 1 (char 0)
[02.09.2021_13-33-31] ‘utf-8’ codec can’t decode byte 0x89 in position 723: invalid start byte
[02.09.2021_13-33-32] ‘utf-8’ codec can’t decode byte 0x89 in position 719: invalid start byte
[02.09.2021_13-33-33] ‘utf-8’ codec can’t decode byte 0x89 in position 719: invalid start byte