Hello Mikołaj Wojdyło,
Thank you for posting in Q&A forum.
On this new computer, you can check these domain accounts are locked by any app (word, excel or OneDrive...) included in Office365.
If you cannot find what locked these accounts, you can try to enable the following audit policy settings on this new machine.
Legacy audit policy:
Audit logon events –> Success and Failure
Audit process tracking –> Success and Failure
After the account locked out again, check if you can see any event ID via Security log on this new machine.
I hope the information above is helpful.
If you have any questions or concerns, please feel free to let us know.
Best Regards,
Daisy Zhou
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