I would say it doesn't matter really. Those 500 subscribers depending on their recently probably aren't actively engaging in your content. You could start a new channel. One thing to remember is that subscribers aren't that important. Making content that is currently popular is how you get more views. Subscribers are not a reliable metric for viewership. It's why channels can have tons of subscribers but hardly any views.

500 subs is nothing. If your content is totally different now then make a new one. 500 is 10% only of 5k, it's 1% of 50k and 0.1 of 500k. Dream big