In the wikipedia article (https://en.wikipedia.org/wiki/Trimethylsilanol), it is written that "Trimethylsilanol is a weak acid with a pKa value of 11. The acidity is comparable to that of orthosilicic acid, but much higher than the one of alcohols like tert-butanol (pKa 19)."

Why is it so? A silicon atom is more electropositive than a carbon atom, therefore the conjugated base will be destabilized by +I effect of the Si(CH3)3 group compared to tert-Bu group.