Understanding Ethereum gas fees

[Antlia Protocol]

I want to understand the gas fees used in running an ethereum validator.
to my knowledge, there is a little gas fee charged every time a validator is run (e.g https://beaconcha.in/validator/79212). my questions are:

Is there a formula or algo which determines the gas fees charged?
Or in other case why it shows a balance of 32.5ETH when only 32ETH were deposited?