I inspected a house that has a sub panel & is being fed by a direct tap to the lower side of the 100 amp main breaker of the service panel. Is this OK.
Sorry no picture
Roy Drangstveit
Did you take pics?
Hard to help you much without them.
I can say this.
The terminal that is feeding the sub conductors must be rated for the number of wires attached to it.
What type of panel is it?
In all likelihood, it’s NOT ok.
As Mike stated, the terminals must be rated for multiple conductors, and typically, when they are rated as such, the conductors must be the same gauge.
Also, you’ve described a situation where the “sub” panel has no over-current protection.