There seems to be something about the country setting on it:
Something that MikroTik forgot to write in changelog that is more important than everything else:
If you had set a country and use frequency mode superchannel, updating to 6.43.8 will set regulatory domain.
What does this mean? If you don't use frequencies in default scanlist, you are going to lose stations.
Set country to no_country_set before upgrading.
Will test it out when I'm back from holidays.
Thanks to @razor1 who spotted this: