Whatever you do, DON'T LIE.
You WILL be found out in the interview. You just will. There are certain things about every programming language that you really only hit by using it to build non-trivial production-ready software on a regular basis but pretty reliably encounter when doing the same.
Interviewers who are probing for weakness are going to ask about these. Or pick interview problems where those considerations apply. So do not under any circumstances lie about your C# experience.
To frame the exact same point differently, if you do lie and they don't figure it out it's actually a signal that you probably don't want to work there.
If you are really an experienced well-rounded developer then write your resume to highlight the generic reusable parts of your skillset. Writing code in your primary development language is only part of being an experienced web application developer. You've got web server configuration, CI/CD pipeline setup and maintenance, cloud services, docker, knowledge of HTTP, SEO, basic architecture, basic SQL and database normalization, Javascript, HTML, CSS, medium-to-advanced git usage, principles of Object-Oriented design, basic Functional Programming concepts, and the list goes on.
You may not have done all of that stuff, but if you are mid-career you probably should have at least touched more than half of it and a developer who can do all of that can almost certainly get up to speed quickly in any mainstream web development language/framework.
If you haven't done most of that then consider getting yourself into a better situation with those qualifications in your current job. Also, and hopefully it goes without saying given my opening sentence, don't lie about your qualifications in those spaces either.
I interviewed a candidate since I first wrote this answer who listed experience with Kubernetes on their resume. That conversation went like this (NOTE: for some context the candidate was already absolutely bombing the interview and their resume was apparently a work of pure fiction, I don't normally have this combative a style of asking candidates questions):
Me: "I see you have experience with Kubernetes. Can you tell me, in broad terms, how to set it up from scratch?"
Candidate: "Well, I've only worked with it a little, and I'm interested in working with it more and learning it more deeply."
Me: "Me too, that's a big part of why I came here in my current role. Since you say you have worked with it some though can you tell me the command for invoking Kubernetes from the shell?"
Candidate: "...I don't know."
Me: "DYHAQFM?"