h6 is a blessing and a curse

The pawn on h6 (or h3) can be both a blessing and a curse. While it provides some breathing room for the castled king, and annoys adventurous bishops, in is often a target for sacrificial attacks. Many juniors (include myself when I was younger), hoped to line up the bishop and queen on the c1-h6 diagonal and blow open the kingside with Bxh6.
Older and more experienced players normally deal with such obvious threats, but sometimes the sacrifice is underestimated. Whether David Howell saw the threat and decided it didn't work, or simply thought Gawain Jones could not play it, is unknown to me, but the fact that it was played resulted in a very entertaining game. Objectively the sacrifice wasn't winning, but it gave Jones enough play that eventually Howell was unable to defend all the squares around the king, allowing Jones to win back the sacrificed piece. After that is was a matter of harassing the exposed king until a winning simplification could be played.

Jones,Gawain C B (2682) - Howell,David W L (2696) [C50]
ch-GBR KO 2018 London ENG (3.2), 12.12.2018