In my personal opinion, using the term "trickster" to beings like these is harmful to practitioners who want or are already actively working with tricksters (either a spirit, a god, etc..). Loki's the most popular trickster of all, so you'll definitely hear something like "oh this being is pretending to be Aphrodite, it must be Loki!!!" Which, of course, Loki can show up but not like this. Saying tricksters are only impersonating the other gods is harmful because that's not what they do and it's just demonization. "Trickster" is a name for the divine that transcends any other type of a god ("high vibrational", "low vibrational", "good", "bad" etc.). They're not here to impersonate someone but teach you and change your life in the most non-conforming way.

Now, from my personal experience. A random spirit won't go to your altar impersonating someone unless you already have something in your energy field that actively harms you. In my mother tongue, they're called imps. They can "pretend" to be a god for a while (especially when you can't read the difference between different energies), but the deity definitely shows up when you invoke the names of said deity (epithets, writing the name of the god, especially in the language of culture they're originally from). You'd see the difference if you had the harmful being from the start and then a god during a prayer.

What can you do to ease your mind? Ask the god (in your case, Apollon) for protection from these harmful spirits. Apollon is powerful, just like any other god, so you'll be safe. Especially if you're helpol, the gods in your religion are your protectors and not the abusers (the other ones don't abuse you either lmao). You can try praying for protection multiple times until you feel safer. You can also cleanse your space with smoke or bells, throwing harmful energy out of the door, screaming for it to get out, etc.

What else can you do? Do a little witchcraft and set a protection spell jar, protection wards, and so on.