When I look at
https://www.openstreetmap.org/node/3034487305 I see the
name tag shown as (shortened to the first six letters):
Poczto
You indicated you typed:
poczta
The difference is the final letter, an "o" in OSM data and an "a" in
what you indicated you typed.
Therefore, as the two differ, I would not expect the app to find
"poczto" from "poczta" using the name tag data.
Where I do see "poczta" is in the operator tag. Which would imply that
the contents of the operator tag are not utilized when searching for a
POI. Overall this seems reasonable, as most users would be searching
for a name, not an operator, since the operator may often have a value
seemingly unrelated to the usual name of an establishment.