No, the highest they have used before bringing out the Su-34 were Su-30s. They have mostly used Su-27s.
There were some fake tweets about Ukr MiG-29 engaging Su-35 in dogfight but those lies have been corrected. Those were 2 Ukr MiG-29s.
No there have been su-35’s over Ukraine. I’ve repeatedly told y’all to not take twitter seriously. Y’all say don’t take twitter seriously. Y’all keep quoting things from twitter and taking it seriously.