Not enough light. New fronds need to develop outdoors under much brighter conditions, otherwise they will elongate terribly, as you see here.

Do you think we can resolve this issue with a stronger plant growth lamp ?

As long as this plant will reside indoors year-round, you are going to have really long leaves. I guess, just accept that.

So, I have had a sago for years in upstate NY and i had this ussue as well. A stronger light wont help unless its very powerful. Moving the light cliser helps a little but wont solve the ussue The fronds are stretching towards the light. What I do is bring the tree outside in the summer, and when it grows new normal fronds, I cut the long ones off. The last few years I've been fortunate and it has worked out so that the fronds grow when its outside. Maybe the tree has ”learned” the cycle of going outside in the summer, who knows? ive had the tree so long now it has a 1’ trunk. By tge way, even uf outdoors it can stretch like this unless its in full sun.

NOT a good houseplant at all. Having said that, I have several large ones that I season outside from March till early December and then, overwinter in a frost free but cold garage. Outside, mine usually go into full sun eventually, but this year, I left them outside in shade and all have flushed or are currently flushing new, normal growth (outdoor light, even in the shade is MUCH stronger). Aside from the light, these also just seem to resent being indoors, they want fresh air. On a positive note, if moved outside, new growth will be normal again.