Your UK State Pension freezes the day you move
Türkiye is on the FROZEN list. The State Pension you start drawing as a Türkiye resident does not receive the annual triple-lock uprating — it stays at the rate that applied when you first claimed (or when you moved, if you were already claiming). Over a 20-year retirement this is the single largest cost most UK movers don't model. The UK-Türkiye Social Security Agreement (1959, in force) covers some matters but does NOT cover State Pension uprating. Private and workplace pensions are unaffected by this rule.
GOV.UK "Country comparison tool: State Pension if you retire abroad" — verify before relying.