There are variations in pronunciation.

Neither my wife nor I pronounce the [w] (I have a General American accent and she has a General Canadian accent).

However, when I experiment by raising my tongue for "er" (transcribed as [ɚ] or [əɹ] or [ər]), I get [wər].

Lower

[ˈloʊ(ə)r] (New Oxford American Dictionary)

[ˈloʊwə̝r̝] (my pronunciation with a raised tongue position)

Interestingly, both the online Collins dictionary and the Oxford Learner's Dictionaries give recorded American pronunciations with an intrusive [w].

Yes, it's a fairly light 'w'.

Yes, we do pronounce the 'w' in 'lower'. Also in 'fewer'.

In modern RP, we would pronounce the second syllable the same is in words such as 'power' and 'flower'.

To be honest, I'm not quite sure how you are imagining a pronunciation of 'lower' without a 'w'. When we say 'low', we finish with our lips tensed and rounded (as if for a kiss!) . We then have two options - to relax if there's nothing following the 'ow' or to release the pursed lips when we add 'er'. This release creates the 'w' sound. It would be very hard not to pronounce a 'w' before the 'er'.

It is a very light "w" that requires time to be able to distinguish. The level of quite-ness varies a little from speaker to speaker, also you may have heard speakers who spoke fast or where not clear speakers. Also there are speakers who have problems with the "w" both native and foreign. The "w" an "v" sound is often difficult for many speakers.

I have sometimes heard speakers who over stress the "w" in lower and their speaking doesn't sound naturally it causes people to notice them. Refer back to the previous sentence where some people have problems with "w"

Good morning @John and @Su.Ki Thank you very much for answering quickly.

@John Can you please elaborate more? I usually hear both with and without "W" equally in both British and American English.

@Su.Ki I would like to confirm if it's not the full W sound, right? Just a little W to connect both vowels smoothly?

Thanks again for your help.