diary entries change date after time zone change

[celebri4n]

After flying from New Zealand to Nepal, all of my diary entries changed their timestamp to one day earlier. I undid this change for all of my entries manually but now it happened again after flying from Nepal to South Africa.

So:
27th of May 2023 -> 26th of May 2023
1st of January 2023 -> 31st of December 2022
etc.

All of my diary entries are all day entries, in case that's relevant.