Start with where and when the position feels stretched
Record which hand position you are using, whether the feeling changes when braking or riding rough ground, how long it takes to appear, and whether you can keep relaxed elbows and normal steering control. Note recent changes to the saddle, bars, stem, hood position, spacers, or frame.
A stretched feeling does not prove that one specific part is wrong. Saddle position, bar shape, controls, frame geometry, mobility, and riding direction can interact.