Premiere Pro 2020/2021 - Bitrate differences for h.264 files

[ALS-Digital2804]

Since Premiere 2020 I have the problem that when rendering h.264 the bitrate at the end is much lower than I had preset.
Example: with a preset of 30 Mbit in the profile "High" and with level 4.1 I get at best a 8 MBit file. In Premiere 2019 and older, this still works fine. What am I doing wrong?

[basil1891]

Hardware encoder? Try software one or switch to HW + CBR mode