Agnosticism is about the inability to have knowledge. Most agnostics desire to conflate knowledge with 100% certainty. I don't believe 100% certainty exists, but I do believe knowledge exists. Hence, it is illogical to equate knowledge with 100% certainty. I believe that knowledge is based on very high probability estimates. I believe that belief is based on significantly high probability estimates (but not as high as knowledge). Neither is based on 100% certainty since 100% certainty doesn't exist. A claim to probability is a claim to knowledge, hence contradicting agnosticism.
If you admit that some definitions of God are more probable than others than you immediately forfeit agnosticism.
Probability implies knowledge of factors that increase or decrease likelihood. Agnosticism excludes knowledge by claiming complete ignorance of all the factors needed to calculate the probability of God's existence - de facto landing on a probability of 50% (the average of all probabilities between 0% and 100%).
If you think the probability of any god is not 50% then you have knowledge and hence can't be agnostic.
Heuristic for measuring an individual's gnosticism vs agnosticism. If they are willing to make the following utterance, then they are gnostic. Otherwise, they are agnostic.
"I know that God doesn't exists"
"I know that I the sun will rise tomorrow"?
"I know that gravity will still be operating when I wake up"?
"I know that my memories of my past are real, and not implanted during my period of sleep"?
"I know that I am not a brain in a vat"?
"I know other minds are as real as mine"?