Previous no symptom TSH 11 but after 3 years Symptomatic TSH 13/9

Diagnosed with subclinical hypothyroidism in 2022 with leg swelling but without fatigue and brain fog took meds for a year then stopped started having brain fog/fatigue what could be the cause of this? back on levothyroxine now. T4 and T3 are around the same 3 years ago and now.