My guess: they rolled the $23M stilled owed him in 2022 from his previous contract into the extension and what he signed is a 5 year, $183M deal with something like a $40M signing bonus.
How that could look for cap purposes:
2022: $2M salary plus $8M prorated signing bonus = $10M cap hit
2023: $30M salary plus $8M prorated signing bonus = $38M cap hit
2024: $33M salary plus $8M prorated signing bonus = $41M cap hit
2025: $37M salary plus $8M prorated signing bonus = $45M cap hit
2026: $41M salary plus $8M prorated signing bonus = $49M cap hit
Note the $13M cap savings in 2022.
Note also that the Rams can convert salary in any of the other 4 years to a signing bonus if they need cap relief down the road.
AlbaNY_Ram