Technically you are not able to use it any more because the limit is 75cm.
If your baby still physically fits in the seat (head contained in the shell) it is unlikely to be dangerous, but it makes sense to look for the next seat fairly soon. If their head is already above the top of the seat, you need a new one immediately.
At 10 months, they need to stay rear facing so you need a seat with rear facing capability. It's safest to stay rear facing as long as you can - you can RF all the way to the booster stage, if you want to.
In terms of next stage rear facing options, there are basically three types of seat.
- Isofix seats up to 105cm, commonly spin types (RF/FF)
- Belt fitted seats up to 18kg/105cm, very basic but budget friendly
- "Extended" rear facing seats up to 125cm.
The belt fitted seats to 105cm are good for spares or holidays but compared with the Coral these will feel like a real step down in quality and features. So I would say you are most likely interested in either an isofix seat up to 105cm, or a 125cm limit ERF seat.
Maxi Cosi do a compatible isofix seat up to 105cm for your current base - the exact model depends on whether you have the 360 base or not. However, they are expensive, nearly £300 for the 360 versoin, whereas there is usually some brand on offer at £200ish where the base is built in - currently Britax Dualfix (RF/FF) and Swingfix (RF only, Swedish plus tested). Or £200/250 for the non-spin version, which doesn't make sense when you can get spin seats for less or the same money.
Worth noting - your baby is on high centiles for height, which means that if they stay on the same curve, a 105cm limit will be outgrown somewhere around age 3.5 - this is OK if you are able to pass the seat on to a younger sibling, but if you are hoping to go straight from that seat to a booster seat, 3.5 is a bit too young ideally. In addition, they are on lower centiles for weight than height. So if they stuck to exactly the same centiles as now, they will be too tall for a 105cm seat but too light to safely use a high back booster seat. This is a bit of a pain.
125cm ERF seats then might be a good option for you. They tend to be belt fitted due to having very high weight limits which overloads the max spec of isofix, though there are a couple of isofix options (these have lower weight limits - not an issue for you - and are more expensive).
Current offers are Britax Safe Way M and Axkid One2 but you could also look at Axkid Movekid, Minikid 4, Avionaut Sky, and Besafe Stretch.