Latex condoms are somewhat biodegradable although not fully biodegradable.
What latex itself is also a natural and biodegradable rubber the latex condoms have additives and chemicals added in the manufacturing process of the condoms which makes the latex condoms less biodegradable so they should not be flushed down the toilet and should be thrown in the trash instead.
Condoms that are flushed don't float back up although they can and do often cause clogs in pipes and sewage systems and lead to costly repairs.
Condoms are not flushable although some people do flush Trojan condoms and other condoms down the toilet.
However you really should never flush condoms down the toilet including Trojan condoms as they can clog the toilet, sewer pipes and even clog the main sewer line and cause problems at the sewer treatment plant.
If you have a septic tank flushing the condoms including Trojan condoms down the toilet could cause issues with your septic tank as the condoms are not biodegradable and won't break down in the septic tank or sewer treatment plant.
When condoms reach the sewer treatment plant they are screened out and then are thrown in the trash with other debris.
Condoms should always be thrown in the trash and not the toilet.
Condoms don't readily dissolve in water like toilet paper does and can cause clogs in septic systems and sewer systems.
Flushed condoms can also potentially end up in oceans, lakes and water treatment plants and lead to pollution and even potentially harm wildlife.
The flushed condoms can cause issues at the sewer plant as well and even clogs which can be time consuming and costly to repair.
Condoms should always be thrown in the trash and wrapped in a tissue or paper bag to avoid any odors and spills.