There is a specific rule requirement to disclose any possible disadvantages in the suitability report. The rule (COBS 9.4.7) can be seen here: http://fshandbook.info/FS/html/FCA/COBS/9/4.
Remember that a disadvantage is different to a risk. For example, there is a risk that investments can fall in value, whereas a disadvantage would be that the recommended product has higher charges than the product being replaced.



Ongoing reviews and value for money
Alistair MacDougall Compliance 2017, 2019, FCA, FOS, MiFID, PI, Update
How can firms ensure clients get value for money in annual reviews?