Chinese and Russian radar experts have made the claim.
US radar experts also make the same claim.
The F-22 can be seen with VHF radars. Given the advances in interferometry and signal processing during the last 20 years, it is now possible to track an F-22 with VHF/UHF radar. This is common knowledge.
New Radars, IRST Strengthen Stealth-Detection Claims | Aviation Week
Yes it is still effective, taking into consideration that stealth is not invisibility it just means detection ranges to detect stealth aircraft are shorter compared to non stealth aircraft.
Undoubtedly, Russian/Chinese advancements in radar technology have been advancing in leaps and bounds in the last decade and some people believe that this makes stealth obsolete. Stealth aircraft have reduced detection ranges so they would have to be closer to the radar to be detected compared to non stealth aircraft.
Take for example the Russian S-400 air defense system which is arguably the most advanced and effective air defense system in the world, it can detect aircraft 600 km away and engage them from 400 km which is quite impressive. It has been reported the f-22's radar signature is the same as a metal marble which is 0.00001 meters squared although this has not been confirmed or denied by the US air force, (note I am sorry I don't know where the squared symbol is on my keyboard so I just typed the word). That means even an air defense system as advanced as the S-400 can detect stealth aircraft about 50 km away, while this may sound like a long distance, stealth aircraft possess the ability to carry long range stand-off ordnance that can be launched from outside this 50km detection zone. So you can launch ordnance outside the radar detection zone and hit the radar without it ever seeing you. An example of some ordnance that can fulfill this role is the JASSM or AGM-158.
So while I admit older 4th generation fighters may be vulnerable to the new SAM sites, stealth aircraft could just go rolling into the radar zone and launch their ordnance up to 230 miles away, seeing as the S-400 detects stealth aircraft 50km away which is about 30 miles away. So you have a weapon which has a range of 230 miles and you have to destroy a radar with it and the radar can detect you only 30 miles away, it is the simplest and most efficient way to take out a radar. Incase you were wondering the weapon with the 230 mile range is the Jassm (AGM-158) so an F-22 raptor or B-2 Spirit could just launch this missile from way outside the detection range and this makes sure the pilot stays out of harm. So yes I do believe aircraft like the F-22 raptor are effective against new advanced radars.
Note that the F-22 is designed to hide it's thermal signature and just like radars the thermal sensors would have to be pretty close to detect the body heat of an F-22 raptor. The Chinese and Russians claim that their new radars can easily see stealth aircraft but the US knows this is only at close ranges and no pilot would be stupid enough to fly close to a SAM site over enemy territory. These advanced radars are the reason stealth aircraft were created in the first place and stealth aircraft like the f-22 do an amazing job of countering these threats for which they were built for.