This is probably not what you want to hear, but I will tell you anyways: If this is your own personal phone, you simply should not install work apps on it. If your employer is ever in legal trouble for example, this makes your personal devices fair game to be subpoenaed, confiscated as evidence, etc. Personal and work data should never be mixed.
Also: Shelter operates entirely locally (unlike most MDMs like Microsoft Intune’s Company Portal) so there isn’t risk there. Not any more risk than your employer allowing work apps to be installed on a personal device in the first place, anyways.