if i have not provided the context to a gem will updating the models from 2.5 to 3.0 affects the context that the chat had?

So, I was having a chat that was active from last 1 month, and i was not so aware about the 'gem' feature from gemini or 'new-project' feature from openai i recently came across that point, so was curious if it would be lost if the models are updated as the weights or the context the 2.5 model had from the chat would be lost ?
–> I mean, I am curious. would love to know what exactly is the feature and how helpful is it.

thank you!!