Russian spies and their coverups != Belarussian KGB\OAC and their coverups.
Russians have the ability act bold on purpose because of their oil and money. They have a massive propaganda machine that will scream all kinds of bs in all directions. Paid politicians all over the world will also side with Russia.
Belarus, does not have that kind of leverage. They have no propaganda machine to create coverups and have to act sneaky.
Like with Pavel Sheremet's murder [3] in Ukraine, they organized it well enough to avoid detection up until 2021. Or a Minsk metro bombing [5] where they just grabbed some dudes and executed them not even a year later.
They often fail ofc. They failed with a cover up of Alexander Taraikovsky's [0] murder and later with Raman Bondarenko's [1]. How they failed with staging a coup attempt with russian PMC soldiers shortly before the election[2] and released all "terrorists" a few months later without any punishment or comments [6].
Do not over sophisticate these people. Belarusian KGB today, in general, is not what it used to be even 20 years ago. Times of people dissapearing into thin air (Zaharenko, Zavadski, Gonchar to name a few [4]) are gone, just like most of the people who were able to pull off stuff like that.
Today's state of it is due to negative selection where the most loyal get to the top, and not the most talented or capable.
[0] https://voicesfrombelarus.medium.com/what-we-know-about-the-...
[1] https://www.rferl.org/a/belarus-bandarenka-lukashenka/311691...
[2] https://www.rferl.org/a/russian-diplomats-meet-detained-vagn...
[3] https://www.reuters.com/article/us-ukraine-belarus-journalis...
[4] https://www.amnesty.org/download/Documents/120000/eur4901320...
[5] https://www.opendemocracy.net/en/odr/minsk-bombers-executed-...
[6] https://www.nytimes.com/2020/09/20/world/europe/belarus-russ...