Aww congrats, mama! That's such a sweet sign na healthy ang baby mo, a few of us in my mum group noticed the same thing around 20 weeks, like suddenly napaka-active lalo during afternoons and evenings talaga. It's totally normal kasi mas nakikita mo ang movements pagka-settled ka na at hindi busy, plus baka active din si baby kapag you're resting or sitting down, mag-enjoy lang ng bonding moments na yan!