I can't change my skin on the minecraft.net website, every time I select "change skin" with the mouse cursor, it loads and returns to the previous page

Sometimes a warning appears on the screen saying "if you have a Java or Bedrock realm, you can adjust the game settings in your profile. To edit your realm, select the realm name on the My Games page."
Furthermore, the button to purchase Minecraft appears sometimes, even though it has already been purchased.