IPhone SE battery glitch

Sometimes when I am using my phone, the battery percentage does not change for hours. When I restart it, it changes to higher than it was before and drops quickly, like this morning, when I saw it had only charged to 35% (my charger doesn’t always work at certain angles, so no surprise there) but it stayed at 35 percent for 4 hours, until a few minutes ago, when I turned it off and back on, it was at 46 and dropped to 40 within a few seconds. This has happened a couple times now, is turning it off and then on again the only solution? Thanks