Can you explain why you think these should match?

I researched requests from IP 146.120.150.*
This is Belarus, both by whois and by the nature of the query.
But I was surprised that it was not listed as a BY country.
I found only one entry for that range in "delegated-ripencc-extended-latest"

ripencc|CZ|ipv4|146.120.0.0|65536|20110712|allocated|cde403b8-c83f-445a-ac85-f5f17f98ecb6

I thought that the aggregated lists by country were generated based on the AS networks received from RIPE.
I must be mistaken.

Can you tell me how the lists by country are formed and on the example of this IP it was not included in the BY country list. I think it will be interesting for everyone.

Sure. The RIR lists are based on data published by the RIRs (which includes RIPE).
Since IP leasing is a thing, you can't assume that only RIR delegated networks are announced by an autonomous system.